TWIN Manual Celcom Electronics Ltd.

The TWIN is designed to provide a reliable interface between telephone equipment and radio systems. The telephone equipment connects simply by plugging into the RJ-11C socket on the front of the interface. A multi-pin socket on the back of the TWIN provides the radio connection. In most cases involving mobile mounted Cellular radios, connection to the radio is simple and the user can install the interface in minutes by using modular cables provided by CELCOM. Connection to PUSH TO TALK (XJ) radios is a bit more involved requiring simple connections to the radio. THE TWIN WILL FUNCTION WITH ANY RADIO OR FAX MACHINE.

The TWIN allows for flexibility in your data transmission requirements. ALL adjustments are accessible from the rear panel allowing for field adjustments if required by the user. The Interface may be moved from radio to radio, or connected to several radios at the same location by using simple A/B switch boxes. It may also be used on all types of radio equipment, FM, AM, SSB, Satellite.

It is important to note that FAX machines do not need to be modified in any way to function with the TWIN. This capability allows any off the shelf fax machine to be used.

RX	Sets radio to phone level (typically -15 dBm)
TX	Sets phone to radio level
TRIP	Adjusts Press To Talk level for half duplex radios
Window	Adjusts OFF HOOK detection threshold

1) Using the cable supplied with the FAX machine, connect the LINE jack to the TWIN.

2) In some cases where the FAX machine does not have a handset or is not programmed to go off hook immediately after pressing SEND, install the supplied shorting plug into the jack on the FAX machine labeled PHONE or external PHONE.

2) Place the call as per usual. If using an operator assisted telephone system, ADVISE the operator that you are placing a DATA CALL.

3) When the called number starts ringing, press “SEND” or “START” on the FAX Machine. If you are not using the shorting plug, you may need to press the SPEAKER or OFF HOOK button or remove the FAX handset from the cradle in order to place or receive a fax.

2) After determining that the call is for the FAX, press the START or SEND button. Make sure that you do not have a document in the send tray or your fax will think that it should be sending it!

1) In most cases, the supplied shorting plug should be installed in the external phone or phone jack on the fax machines. Newer fax machines can be programmed by the FAX supplier to operate in a LEASED LINE mode and do not require the shorting plug.

2) Operating procedures may be different for your particular fax machine. The TWIN will work with ANY RADIO OR FAX MACHINE. If you are having ANY problems with transmitting or receiving, contact CELCOM for assistance.

3) When using some cellular radios, adjust the handset volume to maximum. This provides a standard audio level to which the TWIN has been adjusted. Failure to do this may prevent the FAX from operating.

ADJUSTMENTS

CELLULAR Radios

1) Connect the interface to the radio according to the attached diagrams. Turn the RADIO ON. Make sure that the ON lamp on the TWIN is on. Connect a telephone or a fax with a handset to the TWIN. Pick up the handset, and make sure that the OH lamp turns on. If it doesn't, adjust the WINDOW control until it operates reliably. It is typically set to the 6 o'clock position.

2) Place a call as you normally would to another phone. When the call is answered, pick up the handset on the device attached to the TWIN and listen to the other party. Ask them to talk in a normal voice while you adjust the RX control to a comfortable level in your handset. Best operation appears to be when the level is slightly lower than what you would expect on a normal telephone. The RX level is typically at the 3 o'clock position, but may be different in your application. If you have a TELEPHONE TEST SET, adjust the RX level for -15 dBm. Make sure that the OH lamp is ON when making ALL ADJUSTMENTS.

3) Connect a FAX machine to the RJ-11 jack on the TWIN. Place a call to a local phone, and while listening to this phone, press START on the FAX machine connected to the TWIN, and adjust the TX control to the point where the FAX signal starts to change in audio quality, and then turn it down slightly below this point. This sets the TRANSMIT level to the MAXIMUM point where data can be sent! Trying to get more audio through to the telephone will only REDUCE your data rate and may actually prevent data transmission.

4) If a handset is not connected to the FAX machine, insert the shorting plug in the external phone jack on the FAX. Adjust the WINDOW control so that the OH lamp goes on when you press start, and goes off when the FAX is idle. Cycle the FAX machine several times to ensure that the adjustment is correct. This adjustment is fairly wide. DO not set the control on the edge of its range or you may have erratic operation. Try and get the adjustment centered.

THESE ADJUSTMENTS SHOULD NOT BE ATTEMPTED UNLESS YOU KNOW WHAT YOU ARE DOING. IF YOU HAVE ANY PROBLEMS WITH YOUR TRANSMISSIONS, CALL CELCOM FOR ASSISTANCE. WE CAN HELP YOU ADJUST YOUR RADIO OVER THE PHONE, BUT CALL US ON THE RADIO YOU ARE HAVING PROBLEMS WITH.

3) Connect a telephone or a FAX with a handset to the TWIN, lift the handset and make sure that the OH lamp goes on. If it doesn't, adjust the WINDOW control counter clockwise while the handset is off hook until the OH lamp comes on. Place the handset on hook and make sure that the OH lamp goes off.

4) Break the squelch on the radio and lift the handset. Adjust the RX control for a level just below what you would expect to hear on a normal telephone line or connect a telephone test set and adjust the RX level for -20 dBm.

5) Press start on the FAX machine and adjust the TRIP control to the point where the radio goes into transmit at the beginning of the fax transmission and stops transmitting at the end of the transmission. Fax DATA is sent in small PACKETS and normal operation is for the FAX to alternately transmit and receive at the beginning of a transmission as it goes through the handshaking process. It is important to set the TRIP control so that it follows the handshaking process accurately without adding any delays to the process. Too long a delay at the end of the data packet will prevent the handshake from being completed correctly. If the level is too high, the PTT may operate during received packets. If you feel that the TRIP is set correctly, and you are having this problem, reduce your RX level slightly.

6) Connect a FAX machine to the TWIN. Place a call to a local phone or monitor your transmitted signal on a service monitor, and press start on the FAX. WHILE LISTENING to the transmitted FAX signal, adjust the TX control to the point where the signal just starts to limit or distort and than back off the level slightly. If this level is exceeded, data will not be sent or the speed of transmission will be low. Typical data rates are 4800 BPS however, 9600 BPS is possible. Typical deviation levels are between 2 and 3 kHz.

7) If a handset is not being used with the FAX machine, insert the shorting plug into the external phone jack. Adjust the WINDOW control so that the OH lamp is off when the FAX is idle and goes on when the START button is pushed. Cycle the FAX machine several times to make sure that it is set correctly. Check to make sure that the OH lamp does not flash during FAX transmissions.